All things considered I think you did a great job. There are some things you need to work on however. I think if you learn how to draw skeletal lines and shapes first (reference the tutorials at
www.polykarbon.com for a quick visual example) you will find that your work will improve very quickly. It's a big hump to get over at first, but the results are invaluable. That is the key to drawing anything. You may condsider purchasing a "how to" book on drawing figures. Though the style of Akira Toriyama is unique for DBZ and beyond, everything you learn as an artist applies to your work. If you can draw figures, you can draw DBZ. Also think about cloth physics (one of the hardest things to do in my opinion), this you can learn by observing how clothing reacts to movement and drawing it. You have the ability, just practice to refine your technique.